SCN9A and paroxysmal extreme pain disorder: The original range of inherited conditions associated with SCN9A (i.e. PE, PEPD and CIP) has recently been supplemented with chronic non-paroxysmal neuropathic pain (Dabby et al. 2011), small fiber neuropathies (SFN) (Faber et al. 2012) and partial congenital insensitivity to pain (Staud et al. 2011; Yuan et al. 2011).